The present invention relates to a control knob that incorporates locking provisions which, when operated, serve to inhibit rotation.
Such control knobs, well known for some time and for a wide variety of uses and applications especially but not exclusively on engines and machinery, are devices that encompass a usually round crown rim and a disk or spokes-and-hub wheel, whereby, sometimes with the aid of a handle, the crown rim turns a spindle to which the hub is connected, permitting convenient control or regulating operations.
In most cases these operations take place between positions that are set or determined by the operator without the need or practicality of preventively selecting them with precision or maintaining them in a fixed, secure setting. The majority of the known control knobs, however, do not have locking provisions.
Yet there are cases in which locking the control knob (and with it the spindle turned by it) in or near a certain position can be very convenient and sometimes extremely useful.
In one particularly significant case (but there may be many others), the knob controls the movement of rolling file cabinets: Traditionally, these cabinets that roll in tracks and are in contact with one another when in their idle position, are moved in tandem along the tracks to permit access to their contents, by operating for each of them a control knob whose spindle controls a gear system which activates an element that sets the file cabinet in motion. Access to these file cabinets is often controlled along various authorization levels and is therefore not open to everybody. This creates the need for means that serve to ensure specific access restriction, selectively assigning accessibility to individual cabinets of the rolling files. Moreover, it is equally necessary to prevent ill-intentioned access to the files after working hours, e.g. at the end of the day.
One should also keep in mind that when, as is most often the case, access to the rolling files is open and possible for several persons at the same time, it takes only carelessness on the part of one of them to endanger the others: Even a minor movement of one or more cabinets triggered by the turning of one of the control knobs by a distracted operator can in fact put the others at risk of sustaining a few bruises.